This invention relates to a process for making a bias-cut woven fabric.
Many articles of manufacture comprise a bias fabric as a structural reinforcement. Such reinforcement is disclosed, for example, in U.S. Pat. Nos. 2,519,590, 3,478,613, 4,011,766, 4,024,773 and 4,047,446. These patents disclose the use of bias fabric as structural reinforcement for power transmission belts.
The term "bias fabric" comprises a fabric in which both the warp and fill threads are at an angle other than 90 degrees to the longitudinal dimension of the fabric. In the case of power transmission belts, such bias fabric is employed so that the warp and fill threads are at an angle to the longitudinal direction or axis of the belt. The term "bias fabric" comprises square-woven fabric in which the warp and fill threads cross at an angle of about 90 degrees and the so-called "stress-relieved" fabric in which the warp and fill threads cross at an angle greater than 90 degrees and up to about 160 degrees. Bias fabric is generally rubberized with a friction coat, skim coat or otherwise prepared for vulcanization to other rubber or elastomeric materials.
The square-woven bias fabric is generally prepared by calendering an elastomeric compound to a square-woven fabric and cutting the calendered fabric at an angle of about 45 degrees into relatively wide strips. The individual strips are then lap spliced together by overlapping the end of one strip with another using the tacky elastomeric compound as an adhesive, and are then wound up onto the form of a roll. The fabric may, if desired, be slit longitudinally into relatively narrow tapes of desired width and length.
The so-called "stress-relieved" fabric is generally prepared by cutting a continuous strip from a tubular, square-woven fabric using a cutting angle of about 15 degrees. The continuous strip is dried to a predetermined moisture level and elastomeric compound is then calendered thereto. The drying and calendering steps cause the fabric to neck down, i.e., decrease in width, and the angle between the warp and fill threads to increase from about 90 degrees to about 105 degrees. The calendered fabric is cut at an angle of about .zeta.degrees to the longitudinal dimension of the strip into relatively wide strips. These individual strips are lap spliced together and then wound up into the form of a roll.
The disadvantage of each of the above-described methods for preparing bias fabric is that both methods require the splicing together of individual bias-cut fabric strips. What is desired is a method for producing bias fabric which does not require the splicing together of individual strips.
It has been proposed in U.S. Pat. No. 3,784,427 to produce a bias fabric by cutting a tubular woven fabric into a continuous strip, using a bias cutting angle of between 40 and 50 degrees, coating or impregnating the continuous strip with a binder composition, such as a water-based resorcinol formaldehyde composition or a rubber cement, tensioning the coated or impregnated strip in the widthwise direction to increase the angle between the warp and the filling to an angle about 90 degrees and up to about 160 degrees, and curing the binder composition, thereby stabilizing the warp and filling at the desired thread angle. After curing an elastomeric composition is applied to the strip.
It has now been found that a bias fabric can be produced by a process which is simpler then that described above.
Accordingly, it is an object of the present invention to provide a process for producing a spliceless bias fabric.
Other objects, aspects and advantages of the present invention will be apparent to those skilled in the art from a reading of the following disclosure, the appended claims and the attached drawing.